Variable valve loading injection nozzle



Jan 2 1951 F. M. EVANS ET AL 2,536,542

VARIABLE VALVE LOADING INJECTION NozzLE Filed Feb. 4, 1948 Patented Jan. 2, 1951 VARIABLE VALVE LGADING INJECTIN NOZZLE Fraser Mackie Evans, London, and Wilfrid Edward Walter Nieolls, Pinnen', England, assignors to C. A. V. Limited, London, England Application February i, 1948, Serial No. 6,238 In Great Britain December 31, 1941 Section 1, Public Law 690, August 8, 1945 Patent expires December 3l, 1961 l Claim.

This invention relates to liquid fuel injection nozzles forl internal combustion engines, and has for its object to provide an improved nozzle of the kind having a valve which is subject to a variable spring loading.

The accompanying drawing is -a sectional elevation illustrating diagrammatically a liquid fuel injection nozzle embodying the invention.

In carrying the invention into effect as shown in the drawing, we arrange in the hollow body part a of the nozzle a plunger-type main valve b which at one end is ladapted to control the discharge orifice c of the nozzle. At the end of the valve b remote from the orifice c there is arranged in the body part a a helical compression spring d which through the medium of a flanged plunger-like abutment piece e serves to hold the valve on its seating around the orifice. The Valve b is lifted off its seating in the usual manner against the action of the spring d by the pressure of the liquid fuel to be discharged through the orifice c, which fuel passes through a supply passage f in the body part a and acts on the end of the valve adjacent to the discharge orince.

At the rear end of the spring is arranged an abutment g in the form of a flanged plunger slidable in a cylindric-al bore h in the body part a, and in communication with the bore at the end of the plunger remote from the spring d there is formed in the body part a passage z' leading to the supply passage f which conveys the liquid fuel to the main valve b. The passage z' is controlled by a second plunger-type valve which can be opened by the pressure of the liquid fuel inthe supply passage but which is loaded by a spring 7c suiciently strong to hold this valve closed when the fuel pressure is low. It is preferable and usually more convenient to arrange the second valve y' in the body part a of the nozzle as shown, but it may be arranged in a separate component connected to the said body part if desired.

The body part a is provided with any convenient leakage ducts as l for fuel entering the spaces in the body part occupied by the springs d, 7c.

The above described arrangement is such that when starting the engine, the second valve y' remains closed and the spring d acting on the main valve b then exerts its minimum pressure. But under normal running conditions when in order to provide a short injection period the spring loading on the main valve is required to be increased, the second valve 7' opens under the fuel pressure and allows the pressure to be communicated through the passage i to the plunger g at the rear of the spring d of the main valve b. The effect of this pressure is to increase the compression of the spring d and so increase its loading of the main valve b. The amount of movement that can be imparted to the plunger g by fluid pressure, and thus the amount of compression that can be imparted to the spring d by the plunger, is determined by contact of the flange m on the plunger with a shoulder n in the body part a. When the valve y' re-closes as a result of the engine being brought to rest, the pressure exerted by the spring d on the piston g causes leakage of fuel from the passage i past the piston and/or the cylindrical part of the valve 7, and this leakage relieves the fuel pressure on the piston preparatory to re-starting the engine.

By this invention We are able in a very simple and convenient manner to ensure adequate supply of fuel through the nozzle under starting conditions and at the same time ensure proper control of the supply under normal operating conditions.

The invention is not, however, limited to the particular example above described as subordinate details of construction may be varied to suit different requirements.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

`A liquid fuel injection nozzle for an internal combustion engine, comprising in combination a body part provided with a liquid fuel supply passage and a nozzle discharge orifice, a main valve operable by fuel pressure in the supply passage to control the flow of fuel from the supply passage to the nozzle discharge orifice, a compression spring acting on the main valve in the direction for closing the nozzle discharge orifice, a ymovable member forming an abutment for the end of the spring remote from the main valve, a second spring loaded valve, and a second pasw3 sage through which fuel pressure in the supply passage is transmissible under the control of the second valve to the said member, the second valve being exposed to and operable by the fuel pressure in the supply passage so that when the fuel D pressure is low the second valve remains closed and isolates the said member from the fuel supply passage, but when the fuel pressure exceeds a predetermined amount the second valve opens and allows the fuel pressure to act on the said member for` increasing the compression of the spring acting on the main valve.

FRASER MACKIE EVANS. WILFRID EDWARD WALTER NICOLLS.

4 REFERENCES CITED The following references are of record in the Y file of this patent:

` UNITED STATES PATENTS Y Date Number Name 2,144,132 Walti Jan. 17, 1939 2,173,814 Bischof Sept. 19, 1939 FOREGN PATENTS Number Country Date 43,051 DenmarkV Sept. 16, 1930 232,613 Great Britain Oct. 15, 1925 491,150 Germany Feb. 6, 1930 686,943 Germany Jan. 19, 1940 

